Matt Damon
Last December, the A-list actor lost his father after a long battle with blood cancer.
Shannen Doherty
Now in remission, the actress underwent a single mastectomy in 2015 during her battle with breast cancer.
Tyler Posey
The actor steps out in honor of his mother, who lost her battle to breast cancer at the age of 55.
Sarah Hyland
The Modern Family star is ready to participate in the sixth biennial televised fundraising special.
Josh Brolin
The Hollywood star steps out to help raise money for the non-profit organization.
Katie Couric
The veteran TV journalist, who lost her husband and sister to cancer, is a longtime advocate of the star-studded event's efforts.
Little Big Town
The country music group is set to perform during tonight's telecast.
Michael Ealy
The actor steps out to support the fight against pancreatic and other cancers.
Maddie & Mackenzie Ziegler
The Dance Moms duo share a sisterly moment on the red carpet.
Tony Hale
The Veep star is proud to support co-star Julia Louis Dreyfus, who fought breast cancer earlier this year.
Ed Helms
The actor is ready to help raise money for cancer research.
Sofia Vergara
At just 28-years-old, the actress was diagnosed with thyroid cancer. She underwent surgery and continues to take medication to control her hormone levels.
Max Greenfield
The New Girl actor shows his support for the worthy cause.
Julie Bowen
The Modern Family is joined by two guests at the Stand Up To Cancer fundraising event.
Ken Jeong
The actor's wife, Tran Jeong, beat breast cancer a decade ago. Now, he pays it forward.
Sonequa Martin-Green
The Walking Dead actress strikes a pose before gearing up to raise some money.
Rob Riggle
Also a proud supporter of the Prostate Cancer Foundation, the actor spends his evening at the event.
Marlee Matlin
The Oscar winner, who lost her father to cancer, is all smiles on the red carpet.
Olivia Holt
The actress arrives to this year's Stand Up To Cancer gathering.
Alison Sweeney
The longtime cancer research advocate takes a stand another year.
Jesse Tyler Ferguson
As someone who has experienced his own cancer scare, it's no surprise the actor wanted to show his support.
Jillian Michaels
The television personality makes her dedication to Stand Up To Cancer known.
Mark Harmon
The NCIS star is ready to raise some money for cancer research.
Eric McCormack
The Will & Grace star steps out for the event near and dear to his heart.